P0748: Pressure Control Solenoid "A" Electrical

P0748 is an OBD-II diagnostic trouble code meaning “Pressure Control Solenoid "A" Electrical.” P0748 is a generic powertrain code meaning the transmission control module has detected an electrical fault — voltage or resistance out of the expected range — in the circuit for pressure control solenoid "A". This solenoid regulates hydraulic line pressure inside an automatic transmission, adjusting how firmly the clutches and bands apply based on speed, load, and throttle position. When the computer can't control the solenoid electrically, the transmission often defaults to maximum line pressure or limp mode, so you may feel harsh or erratic shifts, slipping, delayed engagement when shifting into Drive, or being locked into a single gear. Because it is an electrical-circuit code, the fault is usually in the solenoid itself or its wiring rather than a purely hydraulic problem, though contaminated fluid can damage the solenoid. Continuing to drive with slipping and overpressure shifts can overheat the transmission and lead to expensive internal damage, so this should be repaired promptly. This code is most commonly reported on 1994-2001 Ram 1500, 1994-2010 Chevrolet Silverado 1500, and 2002-2013 Chevrolet Avalanche, plus 10 other vehicles, with repair costs ranging from $150 to $3,500.